The solid propellant called for in the original NAA proposal on the service module propulsion system was replaced by a storable, hypergolic propellant. Multitank configurations under study appeared to present offloading capabilities for alternative missions.

1962 Feb 7

Single-engine design for the Apollo service module

On the basis of a study by NAA, a single-engine configuration was chosen as the optimum approach for the service module propulsion subsystem. The results of the study were presented to MSC representatives and NAA was authorized to issue a work statement to begin procurement of an engine for this configuration. Agreement was also reached at this meeting on a vacuum thrust level of 20,000 pounds for the engine. This would maintain a thrust-to-weight ratio of 0.4 and allow a considerable increase in the lunar liftoff weight of the spacecraft.

1962 Mar 3

Aerojet-General named for the Apollo service module propulsion system The Aerojet-General Corporation was named by NAA as a subcontractor for the Apollo service module propulsion system.

The launch vehicle required was a single Saturn C-5, consisting of the S-IC, S-II, and S-IVB stages. To provide a maximum launch window, a low earth parking orbit was recommended. For greater reliability, the two-stage-to-orbit technique was recommended rather than requiring reignition of the S-IVB to escape from parking orbit.

The current concepts of the Apollo command and service modules would not be altered. The lunar excursion vehicle (LEV), under intensive study in 1961, would be aft of the service module and in front of the S-IVB stage. For crew safety, an escape tower would be used during launch. Access to the LEV would be provided while the entire vehicle was on the launch pad.

Both Apollo and Saturn guidance and control systems would be operating during the launch phase. The Saturn guidance and control system in the S-IVB would be "primary" for injection into the earth parking orbit and from earth orbit to escape. Provisions for takeover of the Saturn guidance and control system should be provided in the command module. Ground tracking was necessary during launch and establishment of the parking orbit, MSFC and GSFC would study the altitude and type of low earth orbit.

The LEV would be moved in front of the command module "early" in the translunar trajectory. After the S-IVB was staged off the spacecraft following injection into the translunar trajectory, the service module would be used for midcourse corrections. Current plans were for five such corrections. If possible, a symmetric configuration along the vertical center line of the vehicle would be considered for the LEV. Ingress to the LEV from the command module should be possible during the translunar phase. The LEV would have a pressurized cabin capability during the translunar phase. A "hard dock" mechanism was considered, possibly using the support structure needed for the launch escape tower. The mechanism for relocation of the LEV to the top of the command module required further study. Two possibilities were discussed: mechanical linkage and rotating the command module by use of the attitude control system. The S-IVB could be used to stabilize the LEV during this maneuver.

The service module propulsion would be used to decelerate the spacecraft into a lunar orbit. Selection of the altitude and type of lunar orbit needed more study, although a 100-nautical-mile orbit seemed desirable for abort considerations.

The LEV would have a "point" landing (±½ mile) capability. The landing site, selected before liftoff, would previously have been examined by unmanned instrumented spacecraft. It was agreed that the LEV would have redundant guidance and control capability for each phase of the lunar maneuvers. Two types of LEV guidance and control systems were recommended for further analysis. These were an automatic system employing an inertial platform plus radio aids and a manually controlled system which could be used if the automatic system failed or as a primary system.

The service module would provide the prime propulsion for establishing the entire spacecraft in lunar orbit and for escape from the lunar orbit to earth trajectory. The LEV propulsion system was discussed and the general consensus was that this area would require further study. It was agreed that the propulsion system should have a hover capability near the lunar surface but that this requirement also needed more study.

It was recommended that two men be in the LEV, which would descend to the lunar surface, and that both men should be able to leave the LEV at the same time. It was agreed that the LEV should have a pressurized cabin which would have the capability for one week's operation, even though a normal LOR mission would be 24 hours. The question of lunar stay time was discussed and it was agreed that Langley should continue to analyze the situation. Requirements for sterilization procedures were discussed and referred for further study. The time for lunar landing was not resolved.

In the discussion of rendezvous requirements, it was agreed that two systems be studied, one automatic and one providing for a degree of manual capability. A line of sight between the LEV and the orbiting spacecraft should exist before lunar takeoff. A question about hard-docking or soft-docking technique brought up the possibility of keeping the LEV attached to the spacecraft during the transearth phase. This procedure would provide some command module subsystem redundancy.

Direct link communications from earth to the LEV and from earth to the spacecraft, except when it was in the shadow of the moon, was recommended. Voice communications should be provided from the earth to the lunar surface and the possibility of television coverage would be considered.

A number of problems associated with the proposed mission plan were outlined for NASA Center investigation. Work on most of the problems was already under way and the needed information was expected to be compiled in about one month.

[This meeting, like the one held February 13-15, was part of a continuing effort to select the lunar mission mode].

1962 Apr 30

Apollo service module propulsion engine contract to Aerojet The contract for the Apollo service module propulsion engine was awarded by NAA to Aerojet-General Corporation. The estimated cost of the contract was $12 million. NAA had given Aerojet-General authority April 9 to begin work.

1962 Jun 7

von Braun recommends lunar orbit rendezvous mode for Apollo

Wernher von Braun, Director, Marshall Space Flight Center, recommended to the NASA Office of Manned Space Flight that the lunar orbit rendezvous mode be adopted for the lunar landing mission. He also recommended the development of an unmanned, fully automatic, one-way Saturn C-5 logistics vehicle in support of the lunar expedition; the acceleration of the Saturn C-1B program; the development of high-energy propulsion systems as a backup for the service module and possibly the lunar excursion module; and further development of the F-1 and J-2 engines to increase thrust or specific impulse.

1962 Jun 16

Apollo propulsion to be tested at White Sands NASA announced that the Apollo service module propulsion system would be tested at a new facility at White Sands Missile Range, N. Mex.

1962 Sep 11

Apollo White Sands Missile Range space facility announced

J. Thomas Markley, command and service module Project Officer at MSC, announced details of the space facility to be established by NASA at White Sands Missile Range (WSMR). To be used in testing the Apollo spacecraft's propulsion and abort systems, the WSMR site facilities would include two static-test-firing stands, a control center blockhouse, various storage and other utility buildings, and an administrative services area.

During the Month 1962

Arnold facilities to be used for development of the Apollo reaction control and propulsion systems

MSC reported that Arnold Engineering Development Center facilities at Tullahoma, Tenn., were being scheduled for use in the development of the Apollo reaction control and propulsion systems. The use of the Mark I altitude chamber for environmental tests of the command and service modules was also planned.

1962 Nov 15

Firings of the prototype Apollo service propulsion engine completed

The Aerojet-General Corporation reported completion of successful firings of the prototype service propulsion engine. The restartable engine, with an ablative thrust chamber, reached thrusts up to 21,500 pounds. [Normal thrust rating for the service propulsion engine is 20,500.]

1963 Feb 6

Full-scale firings of redesigned Apollo service propulsion engine Aerojet-General Corporation, Sacramento, Calif., began full-scale firings of a service propulsion engine with a redesigned injector baffle.

During the Month 1963

Allison to fabricate the Apollo SM fuel and oxidizer tanks North American selected two subcontractors to build tankage for the SM: Allison Division of General Motors Corporation to fabricate the fuel and oxidizer tanks; and Airite Products, Inc., those for helium storage.

North American chose Simmonds Precision Products, Inc., to design and build an electronic measurement and display system to gauge the service propulsion system propellants. Both a primary and a backup system were required by the contract, which was expected to cost about 2 million.

1963 May 23

Apollo LEM and CSM to incorporate phase-coherent S-band transponders

NASA Headquarters, MSC, Jet Propulsion Laboratory, MSFC, North American, and Grumman agreed that the LEM and CSM would incorporate phase-coherent S-band transponders. [The S-band system provides a variety of communications services. Being phase-coherent meant that it could also provide Mission Control Center with information about the vehicle's velocity and position, and thus was a means of tracking the spacecraft.] Each would have its own allocated frequencies and would be compatible with Deep Space Instrumentation Facilities.

1963 Jun 20

Definitive contract with Allison for the Apollo service propulsion system propellant tanks North American signed (and NASA approved) a definitive contract with Allison Division of General Motors for the service propulsion system propellant tanks.

1963 Aug 2

Grumman to design the LEM to have a thrusting capability with the Apollo CSM attached

North American asked MSC if Grumman was designing the LEM to have a thrusting capability with the CSM attached and, if not, did NASA intend to require the additional effort by Grumman to provide this capability. North American had been proceeding on the assumption that, should the service propulsion system (SPS) fail during translunar flight, the LEM would make any course corrections needed to ensure a safe return trajectory. [The Guidance and Control Panel, at a meeting on November 29, 1962, had stated that a LEM would be included on all Saturn V flights, thus providing a backup propulsion in case of SPS failure.] On August 6, Robert O. Piland, Acting ASPO Manager, responded by asking North American to investigate the operational and systems aspects of this backup mode before a final decision was made.

1963 Sep 30

Qualification testing began on fuel tanks for the service propulsion system (SPS)

Qualification testing began on fuel tanks for the service propulsion system (SPS). The first article tested developed a small crack below the bottom weld, which was being investigated, but pressurization caused no expansion of the tank. During mid-October, several tanks underwent proof testing. And, on November 1, the first SPS helium tank was burst-tested.

1964 Apr 14

Phase I tests of the Apollo SM engine completed

Firings at the Arnold Engineering Development Center (AEDC) and at Aerojet-General Corporation's Sacramento test site completed Phase I development tests of the SM propulsion engine. The last simulated altitude test at AEDC was a sustained burn of 635 seconds, which demonstrated the engine's capability for long-duration firing. Preliminary data indicated that performance was about three percent below specification, but analysis was in progress to see if it could be improved.

October 15-22 1964

Elimination of propellant dispersal systems for the Apollo SM and LEM accepted by USAF

The Air Force Eastern Test Command concurred in the elimination of propellant dispersal systems for the SM and the LEM. Costs, schedules, and spacecraft designs, NASA felt, would all benefit from this action. ASPO thus notified the appropriate module contractors.

December 16-January 15 1964

Phase II Apollo service propulsion system engine tests begun Phase II service propulsion system engine tests at Arnold Engineering Development Center were begun under simulated high altitude conditions with a successful first firing of 30 seconds. A total of nine firings were completed.

1964 Dec 21

Thermal status of antennas for the Apollo CSM and LEM spacecraft

The Structures and Mechanics Division (SMD) summarized the thermal status of antennas for the Apollo spacecraft (both CSM and LEM). Generally, most troubles stemmed from plume impingement by the reaction control or radiation from the service propulsion engines. These problems, SMD reported, were being solved by increasing the weight of an antenna either its structural weight or its insulation; by shielding it from the engines' exhaust; by isolating its more critical components; or by a combination of these methods.

1965 Jan 18

Qualification testing completed of the tanks for the Apollo service propulsion system General Motors' Allison Division completed qualification testing of the propellant tanks for the service propulsion system.

1965 Jan 26

Thermal effects for a fixed Apollo CSM rendezvous radar antenna At a meeting held at Grumman, RCA presented its study on thermal effects for a fixed rendezvous radar antenna assembly which would be protected from the CSM service propulsion system by a thermal shield.

1965 Feb 5

Apollo SM 001's service propulsion engine static-fired SM 001's service propulsion engine was static-fired for 10 sec at White Sands. The firing was the first in a program to verify the mission profiles for later flight tests of the module. (SM 001 was the first major piece of flight-weight Apollo hardware.)

1965 Mar 27

Test Series I on Apollo spacecraft 001 completed

Test Series I on spacecraft 001 was completed at WSTF Propulsion Systems Development Facility. Vehicle and facility updating in progress consisted of activating the gimbal subsystem and installing a baffled injector and pneumatic engine propellant valve. The individual test operations were conducted satisfactorily, and data indicated that all subsystems operated normally. Total engine firing time was 765 seconds.

April 16-May 15 1965

Qualification testing completed on the fuel tanks for the Apollo SM's reaction control system North American completed qualification testing on the fuel tanks for the SM's reaction control system.

June 16-July 15 1965

Apollo service propulsion engine failures

North American reported two service propulsion engine failures at AEDC and a third at WSMR. At the first location, both failures were attributed to separation of the thrust chamber from the injector assembly; in the latter instance, weld deficiencies were the culprit. Analysis of all these failures was continuing.

July 16-August 15 1965

Apollo LEM redesigned as a backup for the service propulsion system

In order to use the LEM as a backup for the service propulsion system (SPS) to abort the mission during the 15-hour period following translunar injection, Grumman informed North American that some redesign of the spacecraft's helium system would likely be required. This information prompted North American designers to undertake their own analysis of the situation. On the basis of their own findings, this latter group disagreed with the LEM manufacturer:

Before transposition and docking, the two spacecraft would already be on a confirmed free-return trajectory.

During the 15-hour interval, moreover, LEM propulsion would be required only in the event of failures in the SPS and some time- dependent, mission-critical system.

The probability of two such failures during the abort period, North American concluded, was not sufficient to warrant redesigning the helium system.

1965 Aug 12

Recent failures of Apollo titanium tanks at Bell studied

Resident ASPO quality assurance officers at North American began investigating recent failures of titanium tanks at Bell Aerosystems. Concern about this problem had been expressed by the Apollo Test Directorate at NASA Hq in July and MSC started an investigation at that time. The eventual solution (a change in the nitrogen tetroxide specification) was contributed to by North American, Bell Aero Systems, the Boeing Company, MSFC, MSC, Langley Research Center, and a committee chaired by John Scheller of NASA Hq. The penstripe method to find cracks on the interior of the vessels was used to solve the problem. The quality assurance people viewed the failures as quite serious since Bell had already fabricated about 180 such tanks.

1965 Aug 27

Ground testing of Apollo service propulsion system concluded

North American reported that ground testing of the service propulsion engine had been concluded. Also, changing the propellant ratio of the service propulsion system had improved the engine's performance and gimbal angles and had reduced the weight of the Block II SM.

1965 Sep 14

Several changes to the Apollo spacecraft service propulsion engine ordered

As a result of discussions with North American and Aerojet-General, MSC ordered several changes to the service propulsion engine:

redesign of the ablation chamber seals and the flange mountings

modifications to permit ground purging

redesign of the injection hub

doubling of the nominal valve opening time (from 0.3 to 0.6 sec).

These changes applied to all qualification test and all flight hardware.

1965 Sep 21

Indication of certain failures of the Apollo service propulsion system (SPS) not required

ASPO Manager Joseph F. Shea decided that no device to indicate a failure of the secondary gimbal motor in the service propulsion system (SPS) was necessary on Block I spacecraft. Two factors shaped Shea's decision:

procedures for inflight checkout of the vehicle called for gimbaling the service propulsion engine with both primary and secondary drive motors prior to SPS burns;

furthermore, all Block I (i.e., earth orbital) spacecraft would be capable of returning to earth by means of the SM's reaction control system.

This decision did not alter the requirement for such devices on Block II spacecraft, however, and North American was incorporating warning lights on those vehicles to indicate such gimbal motor failures.

1965 Nov 11

Apollo Block I SPS engine altitude qualification test The Block I service propulsion system engine successfully completed the first altitude qualification tests at AEDC.

1966 May 5

Apollo engine testing problems

Engine testing at the Arnold Engineering Development Center (AEDC) had been the subject of discussions during recent months with representatives from MSC, Apollo Program Quality and Test groups, AEDC, Air Force Systems Command and ARO, Inc., participating. While AEDC had not been able to implement formal NASA requirements, the situation had improved and MSC was receiving acceptable data.

In a letter to ASPO Manager Joseph F. Shea, Apollo Program Director Samuel C. Phillips said, ". . . I do not think further pressure is in order. However, in a separate letter to Lee Gossick, I have asked that he give his personal attention to the strict adherence to test procedures, up-to-date certification of instrumentation, and care and cleanliness in handling of test hardware."

March 6-7 1968

Design Certification Reviews of Apollo Apollo CSM 101 and LM-3

Design Certification Reviews of CSM 101 and LM-3 were held at MSC. Significant program-level agreements reached included validation of a 60-percent-oxygen and 40-percent-nitrogen cabin atmosphere during launch; reaffirmation of the February 6 Management Council decision that a second unmanned LM flight was not required; and the conclusion that, in light of successful static firing of the 102 service propulsion system and subsequent analysis, a static-firing of the 101 system was not required.

1968 Mar 22

Concern over problems with leaks in the ball valves for the Apollo service propulsion system

Eberhard F. M. Rees, Director of the Apollo Special Task Team at North American Rockwell, wrote to the company's CSM Program Manager Dale D. Myers to express his concern over persistent problems with leaks in the ball valves for the service propulsion system. Rees doubted that any real progress was being made, stating that the problem persisted despite relaxations in leakage criteria and that qualification failures continued to occur. Rees described a review of the program on March 18 at Aerojet-General Corp. as lacking in factual depth. Also, the company did not appear to be pursuing developmental testing of configurational changes with any degree of vigor. Rees suggested to Myers that his people were on the right track and with management attention the vendor's efforts could be channeled to get some genuine results.

1968 Apr 18

Major requirements for further Apollo SPS testing

Two major requirements existed for further service propulsion system (SPS) testing at the Arnold Engineering Development Center (AEDC), ASPO Manager George M. Low advised Apollo Program Director Samuel C. Phillips. First, the LM docking structure was marginal at peak SPS start transient. While evaluation of the redesigned docking mechanism was under way, final hardware design and production could not be completed until positive identification of the start transient was made through the AEDC test series. Secondly, a modified engine valve had been incorporated into the SPS for CSM 101, which thus necessitated further certification testing before flight (comprising sea-level static firings, simulated altitude firings, and component endurance tests). Low emphasized the need to complete this testing as soon as possible, to isolate any potential problems.

1968 Aug 19

Changes in planning for Apollo flights

In a Mission Preparation Directive sent to the three manned space flight Centers, NASA Apollo Program Director Samuel C. Phillips stated that the following changes would be effected in planning and preparation for Apollo flights:

Saturn V 503 would be prepared to carry CSM 103 and LTA (LM test article)-B on a manned CSM-only mission to be designated the C prime mission.

The objectives and profile of the C prime mission would be developed to provide maximum gain consistent with standing flight safety requirements. Studies would be carried out and plans prepared so as to provide reasonable flexibility in establishing final mission objectives.

All planning and preparations for the C prime mission would proceed toward launch readiness on December 6, 1968.

Apollo-Saturn 504

Saturn V 504, CSM 104, and LM-3 were assigned to the D mission, scheduled for launch readiness no earlier than February 20, 1969. The crew assigned to the D mission would remain assigned to that mission. The crew assigned to the E mission (Frank Borman, James A. Lovell, Jr., and William Anders) would be reassigned to the C prime mission. Training and equipping the C prime crews and operational preparations would proceed as required to meet mission requirements and to meet the newly established flight readiness date.

A memorandum from the ASPO Manager on September 3 summarized the basic and alternate missions for which detailed planning and preparation would be performed. In the basic earth-orbital C prime mission the vehicle configuration would consist of the Saturn V 503 with a payload of 39,780 kilograms (CSM 103 and LTA-B with the service propulsion subsystem fully loaded). Insertion would be into low circular orbit of the earth. The earth-parking-orbit activities would include crew and ground support exercises related to spacecraft system checkout and preparation for translunar injection (TLI; i.e., transfer into a trajectory toward the moon). CSM separation maneuver would occur before TLI.

Alternate earth-orbital missions would include a manned TLI burn to a 6440-km apogee or an SPS burn to achieve a 6,440-km apogee. An alternate lunar orbit mission would include mission planning, crew training, spacecraft hardware, and software to support the mission. In providing support, top priority would be assigned to the lunar orbit mission. The memo indicated that following TLI, simulated transposition and docking maneuvers would be conducted; midcourse corrections and star horizon/ star landmark sightings would be performed during the translunar coast; lunar orbit insertion would be accomplished and a lunar parking orbit established for 20 hours.

On September 13, MSC Director of Flight Operations Christopher C. Kraft affirmed that the impact of supporting the described mission plan had been assessed and no constraints were seen to prevent meeting the launch readiness date. He added that the lunar parking orbit would be established during the course of two elliptic orbits and would be of 16 hours duration, thus giving a total lunar vicinity time of 20 hours.

1968 Dec 9

Launch preparations for Apollo 8

Launch preparations for Apollo 8, scheduled for flight December 21, were on schedule, the NASA Associate Administrator for Manned Space Flight reported. Recent significant steps included a leak and functional test of the service propulsion system on November 26, fuel servicing of the CM reaction control system and the SPS on the following day, hypergolic loading on November 30, and loading of the S-IC stage with RP-1 fuel on December 2. All testing of the Mission Control Center in Houston and the Manned Space Flight Network had also been completed; both support systems were ready for full operational support. Recovery briefings had been given to the flight crew and the final flight plan for Apollo 8 had been issued. If all preparations continued to go smoothly, the final countdown for launch would begin on December 16.